rs1182262731

Variant names:

• chr3-37028927-A-G
• rs1182262731
• NM_000249.4:c.1553A>G

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PM5 PP3

The NM_000249.4(MLH1):​c.1553A>G​(p.His518Arg) variant causes a missense change. The variant allele was found at a frequency of 0.00000657 in 152,170 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H518?) has been classified as Pathogenic.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: MLH1 NM_000249.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.19

Genes affected

MLH1 (HGNC:7127): (mutL homolog 1) The protein encoded by this gene can heterodimerize with mismatch repair endonuclease PMS2 to form MutL alpha, part of the DNA mismatch repair system. When MutL alpha is bound by MutS beta and some accessory proteins, the PMS2 subunit of MutL alpha introduces a single-strand break near DNA mismatches, providing an entry point for exonuclease degradation. The encoded protein is also involved in DNA damage signaling and can heterodimerize with DNA mismatch repair protein MLH3 to form MutL gamma, which is involved in meiosis. This gene was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). [provided by RefSeq, Aug 2017]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-37028925-ACA-AT is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.796

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MLH1	NM_000249.4	c.1553A>G	p.His518Arg	missense_variant	Exon 13 of 19	ENST00000231790.8	NP_000240.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MLH1	ENST00000231790.8	c.1553A>G	p.His518Arg	missense_variant	Exon 13 of 19	1	NM_000249.4	ENSP00000231790.3

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152170 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000192

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152170 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74330

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000192

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:2

Aug 07, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.H518R variant (also known as c.1553A>G), located in coding exon 13 of the MLH1 gene, results from an A to G substitution at nucleotide position 1553. The histidine at codon 518 is replaced by arginine, an amino acid with highly similar properties. This variant was identified in an individual with early-onset ampullary cancer and no family history of cancer (Yin L et al. JAMA Netw Open, 2022 Feb;5:e2148721). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Oct 24, 2018

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary nonpolyposis colorectal neoplasms Uncertain:1

Mar 28, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces histidine, which is basic and polar, with arginine, which is basic and polar, at codon 518 of the MLH1 protein (p.His518Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with ampullary cancer (PMID: 35171259). ClinVar contains an entry for this variant (Variation ID: 483592). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MLH1 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Pathogenic	0.43	D
BayesDel_noAF	Pathogenic	0.38
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.94	D;.;.;.;.;.;T;D
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.49
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.85	T;T;.;.;.;T;T;T
M_CAP	Uncertain	0.14	D
MetaRNN	Pathogenic	0.80	D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.36	D
MutationAssessor	Pathogenic	2.9	M;.;.;.;.;.;.;.
PrimateAI	Uncertain	0.51	T
PROVEAN	Pathogenic	-6.3	D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.79
Sift	Uncertain	0.011	D;D;D;D;D;D;D;D
Sift4G	Uncertain	0.013	D;D;D;D;D;D;D;D
Polyphen		0.99	D;.;.;.;.;.;.;.
Vest4		0.55
MutPred		0.43		Gain of solvent accessibility (P = 0.0584);.;.;.;.;.;.;.;
MVP		0.96
MPC		0.35
ClinPred		0.98	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.93
gMVP		0.75

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1182262731; hg19: chr3-37070418; COSMIC: COSV105856847; COSMIC: COSV105856847;